The present invention relates to a cleaning device for cleaning a printhead of an ink-jet printer that carries out printing by ejecting ink droplets onto a recording medium.
The ink-jet printer ejects ink droplets onto a recording medium from a plurality of nozzles formed on an ink ejecting surface of a printhead by applying instantaneous pressure to the ink within the nozzles. The instantaneous pressure is generated, for example, by elements that convert electrical energy into mechanical energy, such as a piezoelectric element, or elements that convert electrical energy into heat.
The ink-jet printer prints characters and images by ejecting ink droplets onto the recording medium and thereby forming a plurality of small dots thereon. A great advantage of such an ink-jet printer is that it can provide a high—quality color image printer of a relatively simple structure by ejecting different color inks from different nozzles of the printhead. However, it should be noted there are also some problems typical among ink-jet printers.
One of such typical problems is that the ink adheres to the ink ejecting surface or nozzles of the printhead during the printing operation.
The ink adheres to the ink ejecting surface or nozzles when bubbles are generated in the ink within or near the nozzles due to temperature increase within the printer as a result of a long, continuous use thereof. These bubbles not only hinder the ink droplets ejected from the nozzles to fly toward the recording medium along expected trajectories, which causes deterioration of printing quality, but also atomize the ejected ink. The atomized ink suspends in the vicinity of the ink ejecting surface, instead of flying toward the recording medium, and a part of them adheres to the ink ejecting surface or nozzles.
The adherence of ink to the ink ejecting surface or nozzles may occur even if the bubble mentioned above are not generated. For example, some of the ejected ink droplet bounces back from the recording medium and adheres to the ink ejecting surface.
If the printer is not used for a long time with the adhered ink left on the ink ejecting surface or at the nozzle opening, the nozzle will be clogged with dried ink. Once the nozzle is clogged, the print quality begins to fade or it becomes unprintable since the amount of ejected ink decreases or no ink can be ejected.
The clogging of the nozzle with dried ink cannot be removed by merely applying pressure to the ink with the piezoelectric element or heating element mentioned above. Therefore, various methods for preventing or removing the clogging of the nozzle are provided.
Typical methods for preventing or removing clogging of the nozzle include capping, wiping, ink suction, and preparative ink discharge (or flushing).
In capping, the ink ejecting surface of the printhead is tightly covered with a rubber cap member to prevent drying of the ink. The cap member covers the ink ejecting surface, for example, when the ink-jet printer is not in use for a long time, or, over the interim time period between one printing cycle and another.
In wiping, the ink ejecting surface of the printhead is rubbed with a blade like member at a predetermined timing or predetermined interval to wipe the ink ejecting surface clean.
In ink suction, the ink is removed from the nozzle under suction at a predetermined interval, timing, or step. In preparative ink discharge or flushing, minute dust of paper and/or fiber, for example, and small ink clots are removed from the nozzles by flushing ink from the nozzles.
It should be noted that one or a combination of the above-mentioned methods are typically used in the inkjet printer to prevent the clogging of the nozzles of the printhead.
If wiping is carried out, the blade should be cleaned to remove the ink adhered thereto. Otherwise, the wiping becomes ineffective or ink remaining thereon drops down and makes the printer dirty. Typically, the ink remaining on the blade is removed by bringing the blade into contact with an ink absorber, or by utilizing the springing back of the blade after being bent.
Devices that prevent or remove clogging of the nozzle by practicing the above-mentioned methods are called cleaning devices or recovering devices. Such cleaning (recovering) devices are essential for the ink-jet printer to maintain high quality printing.
The ink-jet printer disclosed in the above-mentioned Japanese Patent Publication, however, requires much time for the cleaning operation since the printhead is once moved out of the printing area, for allowing wiping of the ink ejecting surface with the cleaning blade, and then moved back to the printing area for allowing the cleaning blade returning to the initial position without coming into contact with the printhead.
Japanese Patent Application Provisional Publication HEI 11-138857 discloses an ink-jet printer in which a cleaning blade wipes off an ink ejecting surface of a printhead, and then moves toward an ink absorber so as to remove the ink adhered to the tip portion thereof by rubbing the tip portion against the ink absorber. The cleaning blade is bent by the ink absorber, springs back as it leaves the ink absorber and thereby scatters or removes the ink adhered to cleaning blade at portions other than the tip portion. The cleaning blade is placed in a blade holder that is coupled to a disk via a link mechanism. The disk rotates to move the blade holder, and hence the cleaning blade, up and down. After the ink adhered to the cleaning blade is removed, the cleaning blade is moved down by rotating the disk so that the cleaning blade does not come into contact with the ink ejecting surface.
Since the printer disclosed in the above mentioned publication lifts the cleaning blade up when the ink ejecting surface of the printhead is to be wiped, and moves down the cleaning blade when the cleaning blade is to be returned to the initial position, the printer requires a complicated mechanism that utilizes a rotating disk to move up and down the blade holder and also an additional motor for driving the disk.
Therefore, there is a need for a cleaning device that is capable of cleaning a printhead of an ink-jet printer with a simple structure.